All Tesla vehicles include power-folding mirrors as standard for years now. Some older Model S cars that did not have this feature may be retrofitted.
Most VINs higher than P12141 have the wiring in place and can be upgraded for $1,600. For cars without the power mirror wiring, the upgrade is $3,200. Pricing confirmed with Tesla for work in California, April 2014, and includes labor and taxes. The newest cars are easier to retrofit, and some owners have had the work done for as little as $1100. Check with a service center for availability and current pricing, which may vary by region.